How sensitive is radionuclide scanning in the diagnosis of lower gastrointestinal (GI) bleeding (LGIB)?

Updated: Jul 26, 2019
  • Author: Burt Cagir, MD, FACS; Chief Editor: BS Anand, MD  more...
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Answer

Nuclear scintigraphy is a sensitive diagnostic tool (86%) and can detect hemorrhage at rates as low as 0.1 mL/min (0.1-0.5 mL/min), as opposed to angiography, which detects bleeding at rates of 1-1.5 mL/min. This technique is reportedly 10 times more sensitive than mesenteric angiography in detecting ongoing bleeding, but it suffers from a low specificity (50%) compared with endoscopy or angiography due to its limited resolution; consequently, many investigators recommend that scintigraphic imaging be used primarily as a screening examination to select patients for mesenteric angiography.

There is also ongoing debate about whether nuclear scintigraphy is effective in determining the source of GI bleeding in patients before obtaining angiography, as findings have been mixed regarding its diagnostic yield with or without a preceding tagged RBC scintigraphy. [5] However, RBC scintigraphy appears to be more sensitive for bleeding compared with computed tomography (CT) angiography (CTA) or multidetector row CT scanning, although CTA is more expedient and accurate as a screening test. [5]


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